Removal of surface metal by shaving

ABSTRACT

The removal of surface metal from bars, rods, tubes and the like by the use of a shaving tool which is preheated to elevated temperature to enhance tool life and surface finish of the work processed therethrough.

nited States Patent [191 Zavodny, Jr. 0

[ REMOVAL OF SURFACE METAL BY SHAVING [75] Inventor: George Zavodny,Jr., Palos Hills, 111.

[73] Assignee: La Salle Steel Company, Hammond,

Ind.

[22] Filed: Sept. 1, 1972 [21] Appl. No.: 285,897

[52] US. Cl. 90/24 R, 82/1 C, 83/170, 29/95.1, 29/106 [51] Int. Cl. B23b3/00, B23d 1/00, B26d 1/00 [58] Field of Search 82/1, 1 C; 29/106, 95.1;90/24, 24 A, 24 B, 24 C, 24 D, 24 E, 24 F; 83/170, 171

[56] References Cited UNITED STATES PATENTS 3,168,004 2/1965 Zavodny,Jr. et a1 90/24 1 Jan. 22, 1974 2,477,411 7/1949 King 90/24 X 972,43610/1910 Clark 29/95.1 X 3,491,651 1/1970 Pascoe 29/106 2,161,570 6/1939Harris 29/106 X 2,059,236 11/1936 Holslag 82/1 C X 2,706,234 4/1955 Macy82/1 C X 2,706,238 4/1955 Blaser 83/170 2,931,263 4/1960 Johnson et a183/170 X Primary Examiner-Harrison L. Hinson Attorney, Agent, orFirm-McDougall, Hersh et a1.

[5 7] ABSTRACT The removal of surface metal from bars, rods, tubes andthe like by the use of a shaving tool which is preheated to elevatedtemperature to enhance tool life and surface finish of the workprocessed therethrough.

7 Claims, No Drawings 1 REMOVAL OF SURFACE METAL BY SHAVING Thisinvention relates to removal of surface metal from bars, rods, tubes andother members of repeating cross-section by means of a shaving toolwhich engages the surface to effect removal of material as the work isdisplaced therethrough.

in the previously issued U.S. Pat. No. 3,168,004, description is made ofa process for metal removal by the use of a shaving tool by which thebar, rod or tube is advanced for removal of surface metal as the work isadvanced therethrough. As described in the aforementioned patent, themetal is heated in advance of passage through the shaving tool to atemperature sufficient to avoid the buildup of material on the edge ofthe tool, generally referred to in the trade as built-up edge. Thebuildup of metal on the edge of the tool interferes with its cuttingefficiency and results in an undesirable surface finish on the work thathas been processed through the tool.

More recent investigations have indicated that poor tool life and poorsurface finish results from cracking which occurs on the cutting edge ofthe tool on both the rake and clearance faces of the tool. Such crackingis observed as radial cracks which are initiated after a short period ofuse of the shaving tool and which increase in number and in intensity,by lengthening and widening, during continued use of the tool. Thewidening'cracks show up as fins on the surface of the work, whichrequires removal by subsequent, rather expensive, surface conditioningoperations.

Soon, such cracking extends to the point where adjacent cracks join andthe piece of the cutting edge in between falls out. The result is suchunacceptable surfacefmish on the metal processed through the tool asrequires removal and replacement of the shaving tool. This condition mayoccur within the period of work entailed in the processing of a smallnumber of bars or rods through the shaving tool.

Such short tool life is undesirable not only by reason of the cost ofthe tool but, more importantly, from the standpoint of the down time ofthe equipment for replacement of the tool as well as the amount of laborthat is required for removal of the inadequate tool and replacement withanother. Also, the last work processed through the inadequate tooleither requires above average surface condition correcting operations orhas to be scrapped.

Thus, it is an object of this invention to provide a means by which theuseful life of the .shaving tool can be increased with resulting lowertool cost and more efficient utilization of the apparatus as well asbetter control of the surface finish of the work processed through thetool with subsequently either lower work surface condition correctingcosts or lower scrap costs.

It has been found that the foregoing objectives can be achieved by thesimple expedient of preheating the shaving tool, separate and apart fromor in addition to the heating of the metal work piece as described inthe aforementioned patent. Tool life and consistency of quality of workfrom the standpoint of the finish of the freshly cut surface of the workpiece are noticeably improved when the shaving tool is preheated, beforeeach work piece is processed therethrough, to a temperature of at least500 F and preferably within the rangeof 500 F to l,300 F and morepreferably to a temperature within the range of 750 F to 1,000 F. Whilethe above applies chiefly to work pieces formed of steel, there isreason to believe that the concept described is equally applicable tometal work pieces generally with preheat of the tool to a temperature aslow as 200 F for non-ferrous metals or up to about l,800 F for suchexotic metals as titanium, tungsten, molybdenum and high carbon or highalloy steels.

Tool preheat can be achieved by various conventional means, such asresistance heaters wound about the tool or embedded within the tool orits support, or by means of a heat exchange fluid, such as a moltenmetal circulated through channels in the tool beyond or at its support.

The improvement that is capable of being achieved by the practice ofthis inventioncan best be illustrated by reference to the followingexample in which tool life was measured by the number of steel barscapable of being processed through the tool to effect removal of surfacemetal at various preheat temperatures for the shaving tool.

Use was made of steel bars of the same composition having a diameter of1 /5 inches and a length of about 15 feet. The work was processedthrough the shaving tool at a linear speed of about 60 feet per minuteand the shaving tool was dimensioned to take a radial depth of cut ofabout 0.020 inch.

One series of bars were processedthrough the tool at room temperatureuntil the first radial crack appeared. These runs were repeated with thetool preheated to various temperatures up to 1,000F and the number ofbars processed through the tool to first cracking was recorded asrepresentative of the life of the tool under the operating conditions,which were the same except for tool preheat temperature. The results areset forth in the following cable which relates the numbers of barsprocessed before appearance of the first radial crack, as representativeof tool life, versus temperature of the tool before shaving each bar.

Temperature of Tool life in number of shaving tool F bars shaved beforeappearprior to shaving ance of first radial crack each bar Roomtemperature 500F 750F No cracks after more than bars I000F No cracksafter more than 70 bars It will be seen from the results that the firstradial crack developed after only 15 bars had been processed through thetool at room temperature. This number was increased to 31 bars when thetool was preheated to a temperature of 500F before each bar was shaved.

An unexpectedly marked increase in tool life was experienced when thetool was preheated to a temperature above 500 F. At 750 F and at 1,000 Fno cracks were detected after more than 70 bars had been processedthrough the shaving tool.

The steelbars processed through the shaving tool, at 750 F to 1,000 F,and up to the 31st bar at 500 F, and up to the 15th bar at roomtemperature, all had acceptable surface qualities which did notnecessitate surface refinishing after removal of the surface metal bythe shaving tool.

It will be apparent from the foregoing that I have provided a simpletechnique by which the useful life of the shaving tool can be markedlyincreased while simultaneously improving the finish of the surface ofthe metal being worked.

It will be understood that changes may be made in the details ofconstruction, arrangement and operation without departing from thespirit of the invention, especially as defined in the following claims.

I claim:

1. In the process of removal of surface metal from elongate work piecesof repeating cross-section by means of a shaving tool through which thework is processed for continuous removal of surface metal during therelative movement between the work and tool, the improvement wherein thelife of the tool is increased and the finish of the freshly cut surfaceis improved by preheating the tool to elevated temperature before thework is processed therethrough.

2. The process as claimed in claim 1 in which the tool is preheated to atemperature within the range of 200 F to l,800 F.

3. The process as claimed in claim 1 in which the tool is heated to atemperature of at least 500 F for steel work pieces.

4. The process as claimed in claim 1 in which the tool is heated to atemperature within the range of 500F to 1,300 F.

5. The process as claimed in claim 1 in which the tool is heated to atemperature above 200 F for non-ferrous metal work pieces.

6. The process as claimed in claim 1 in which the tool is heated to atemperature up to l,800 F for high meltwork pieces are in the form ofbars, rods and tubing.

1. In the process of removal of surface metal from elongate work piecesof repeating cross-section by means of a shaving tool through which thework is processed for continuous removal of surface metal during therelative movement between the work and tool, the improvement wherein thelife of the tool is increased and the finish of the freshly cut surfaceis improved by preheating the tool to elevated temperature before thework is processed therethrough.
 2. The process as claimed in claim 1 inwhich the tool is preheated to a temperature within the range of 200* Fto 1,800* F.
 3. The process as claimed in claim 1 in which the tool isheated to a temperature of at least 500* F for steel work pieces.
 4. Theprocess as claimed in claim 1 in which the tool is heated to atemperature within the range of 500*F to 1,300* F.
 5. The process asclaimed in claim 1 in which the tool is heated to a temperature above200* F for non-ferrous metal work pieces.
 6. The process as claimed inclaim 1 in which the tool is heated to a temperature up to 1,800* F forhigh melting point metals and alloys.
 7. The process as claimed in claim1 in which the work pieces are in the form of bars, rods and tubing.